1. Technical Field
The present invention relates in general to the field of computers, and in particular to network based computers. Still more particularly, the present invention relates to a method and system for maintaining software-based Internet Small Computer System Interface (iSCSI) communication between a computer and a secondary storage if an operating system (OS) anomaly in the computer disrupts the operation of an iSCSI network interface driver.
2. Description of the Related Art
Two ongoing improvements to modern computers are speed and resource sharing. Computers such as blade server computers, which have multiple server blades in a single server chassis, have processors and input/output (I/O) busses that continue to increase in speed and bandwidth capacity. The same is true for secondary memory devices such as hard drive arrays. However, devices that allow computers to communicate remotely with secondary memory devices often cause a data bottleneck.
For example, consider the prior art network topology depicted in FIG. 1. A computer 102 is shown having an operating system (OS) 104, which includes a Small Computer System Interface (SCSI) driver 106. SCSI driver 106 allows data to be put on a SCSI bus (not shown) in computer 102, to which can be connected secondary storage devices such as local hard drives (also not shown).
In an effort to promote scalability and resource sharing, computer 102 uses Internet SCSI (iSCSI). iSCSI is an Internet Protocol (IP) based storage networking standard that has been developed by the Internet Engineering Task Force (IETF), whose current iSCSI standard is herein incorporated by reference in its entirety. Data destined to a storage device on a SCSI bus is wrapped in an IP packet, and sent over the Internet to a remote storage device, which unwraps the IP packet to recover the SCSI commands and data. This function of wrapping and unwrapping SCSI commands and data for computer 102 is performed by iSCSI packaging software 108 found in a hardware iSCSI Host Bus Adapter (HBA) 110, which typically is coupled to a Peripheral Component Interface (PCI) bus 112 in computer 102.
Hardware iSCSI HBA 110's main components include a processor 114 and a Network Interface Card (NIC) 116. Processor 114 utilizes instructions from iSCSI packaging software 108 to wrap/unwrap the IP packets, and NIC 116 affords communication between computer 102 and a network 118, which may be an Ethernet, Internet, or any other network capable of supporting the IP protocol.
The IP/iSCSI packets are communicated with an iSCSI target 120, which is the server component of a Storage Area Network (SAN), which includes a secondary memory represented as a Hard Drive Array (HDA) 122. Thus, data to be written to and read from HDA 122 by computer 102 is able to be communicated via network 118, which allows HDA 122 to be at any remote location away from computer 102.
As noted above, hardware iSCSI HBA 110 is a main bottleneck to data traveling between HDA 122 and computer 102. There are several reasons why this is the case, including speed constraints inherent in hardware iSCSI HBA 110's processor 114 and NIC 116. Thus, there is a need to develop a method and system that avoids this hardware bottleneck.